Space telegraphy.



L. DE FOREST.

SPACE TELEGRAPHY.

APPLICATION FILED JAN.29,1907. 979 276, Patented Dec. 20, 1910.

' 3 SHEETS-SHEET 1.

WIT E5555: Q Pg-2- L. DE FOREST.

SPACE TELEGRAPHY.

. APPLIOATION FILED mime, 1907.

' Patented Dec. 20, 1910.

3 SHEETS-SHEET 2.

L. DE FOREST.

SPACE TELEGRAPHY.

APPLICATION FILED JAN. 29, 1907.

979,276 Pateuueol Dec. 20, 1910.

3 SHEETS-SHEET 3.

LEE on ronns'r, on nnw'ronx, NpYQ, nssrenon, BY unsnn nssrenmnnrsj'ro 'nn 'rntnrrronn 00.,

FOREST RADIO A conrom'rron on rnw YORK. p

sracn TELEGRAPH; I

To all who m it may concern:

Be itknown that I, LEE DE Fonnsr, 'a citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented anew and useful Improvement in Space Telegraphy,

. of which the following is a specification.

My invention relates to electromagnetic wave radiating systems,'-space telegraph or telephone systems,and its object is to provide a system by means of which electromagnetic waves which are of great persistency,

i althou h not continuous, may be radiated.

' usually the primary of an oscillation trans denly. disturbing the electrical equilibrium.

t ticker.

' ously oscil or oscillating circuit cons1sting of a condenser-and an inductance, the latter being former, together with a spark-gap for sudof such circuit by discharging said condenser, there is a limit to which the persistence may be increased with a given frequency and a given amount of energy ab sorbed, for the energy absorbed by such so? norous circuit, on the'one hand, and the persis'tence function and frequency, on the other hand,'are respectivel direct and reciprocalfunctions of the capacity thereof. It has been,

pro osed therefore to employ continuously osci lating circuits consisting, inter alia, of the so called singing-arc circuit, or a circuit in the nature of a singing-arc circuit having a source of direct current connected through lar e ohmic resistance to the terminals of said ap. In a wireless telegraph system employing either of such continuating circuits to energize the transmitting antenna-1t is necessary to sup.

ply a device at the receiving station to com-- mutate theenergy in the local receiving circuitii avariaole zero indicating device, suchv asja. telephone receiver, 18 to be employed,

such device being commonly known as a By means ofthe presentinvention 1 am r circuit.

able to obtain as great a persistencyas is, desirable while at the same time reducing.

the energy output required for the radiation of continuous electromagnetic Waves and obviating the necessity. for commutatingor interrupting the current in the receiving In the figures, C is. acondenser, L L" are inductances, R R are resistances which may In t e employment of the usual sonorous.

or may not be inductive resistances, R is a resistance which preferably 18 inductive, M 1s a transformer, A is a source of vibratory tion.

whichmay both be metal or both carbon, or one of which may be metal and the other carbon. The electromotive force impressed upon the arc electrodes preferably is such that thetime rate of change of its am litude vis first abrupt, then slow or practical y concontinuation of a halt-cycle, and finally ab ,rupt as shown graphically in Fig. l? in whic the curve (1) represents the'variation with time of the amplitude of said electromotive force. Such electromotive force may rent generator giving what is commonly -known as a fiat-top 'electromotive force wave. 1 do not, however'limit myself to an electromotive force having this particulartime-amplitudevariation. The resistances or, more generally, the impedances, it It need not be employed and if the electrornotive force of the source A is of the order 1000. volts it :otherwise preferably is of the step-up type.

The-separation of the electrodes S preferably is such that the voltage across the ga will rise abruptly to its full value as indi- @cated' on curve (1) at 3, before the con denser C begins to discharge, and frrunv this gins to tall. as indicated on curve (1) at a,

electromoti've force, K is a key, V is an elevated conductor and E is an earth connec'-' stant throughout the greater portion of themay eliminate the transformer M, which.

;an und'arnped train or" oscillationagraphi cally shown at- 2, will be developed in the circuit L G S. The energy of these oscillationsmay he translated to the antennaV in- Specification of Letterslatent. Patnted Bed, 20, 1910 In Figs. 1 and 2, S represent arc electrodes 2 beobtained by means of an alternatingc'ur-i timeuntil the time at which the voltage bea 7 any suitable manner, such for example as indicated in Fig. 1, in which the antenna is adjustably connected to the inductance L.

The system shown in Fig. 2 is essentially the same as that above described in connection with Fig. l with the exception that a rectifier D may be connected in the system in any suitable manner so that the polarity of the potentials applied to the electrodes'by the source A is never reversed, in which case, as indicated in Fig. 2, the second half cycle, graphically shown by curve (1), is suppressed. In either case the time interval elapsing between points 3 and. 4 will be a considerable fraction of a second, for example, one two-hundredthof a second, so that a very large number of practically undamped oscillations will take place in, the circuit L C S between the time the applied pressure rises sufiiciently to efiect the first discharge and the time said pressure begins to fall. By way of example, if the time-period of the circuit L C S is one two-hundred-thousandth of a second, one thousand complete undampedoscillations will take place in saidcircuit during each half-cycle in the case above assumed. In such case, it will suffice to so proportion the tuned receiving circuit that its electromagnetic timeconstant is one two-hundredth of a second to enable the currents developed therein to reach the steadystate so that in said circuit the current amplitude will be equal to the ratio of the applied pressure by the ohmic resistance. Thus it will be seen that I gain by-means of the present invention all the advantages of absolute continuity of oscil1ation while at the same time greatly reducing the output of energy required therefor. Furthermore vibratory currents of the required potential are easier to generate and control than the direct currents heretofore used for obtaining continuous electrical 0s cillations. It will be understood of course that as soon as'that persistencyis obtained which will permit the currents in the receivin circuit to reach their steady state, so' or oscillations of the frequency to tion is that the telephone receiver in the receiving system WlllOh is associated in the usual we with an oscillation detector, will give fort sounds having a rate of variation equal to that of the current delivered by the source A, to the end that no local circuit interrupter will be required.-

In the systems shown in Figs. 3, 4 and 5,

the device indicated at S consists in an evacuated vessel inclosing a plate P and a meme filament F which may be heated to incandescence by the battery '13, as in Fig. 8, or by current conducted thereto by leads from the points'a b of the primary of the transformer M, as in Fig. 4, or by currents conducted thereto by lcads from the points c of the autotransformer M, as in Fig. 5. It will be understood of course that the member F may be any heated or glowing body as, for example, a Nernst-lamp glower. The conductivity of the device S is unilateral, being from the nonheated member P to the heated member F, and the rectifying effect of S will be practically'perfect within a certain high-voltage limlt, beyond which limit a relatively small amount of current will flow from F to P. Although-this limit may be reached ,and exceeded on account of the resonant rise of potential in the circuit L C S, the efficiency-of rectification will nevertheless be high.

In virtue of the rectifying efiect of the device S',,the dlscharges-of the condenser, C in Figs.v3, i and 5, within the above mentioned high voltage limit, will be unidirectional and not oscillatory, and only during 'the half-cycles in which that armature of the condenser which is connected to the plate P is charged positively will there be any high frequency pulsations in the'circuit- L C S, as indicated in Fig.- 5. Thus if the generatorA deliver an alternating current of 60 cycles per second, there will be sixty periods per second during which high frequency ulsations are being created in circuit L S (or M C S, Fig. 5) alternating with sixty periods of rest. In Fig. 5, curve (1), 3 and t have the same significance as in Figs. 1 and 2, and 5 represents graphically the variation with time of the high frequency unidirectional pulsations above referred to, while curve (1) represents one of the half cycles during which no pulsations are created. 1

Any suitable connection or. con ling between the circuit of the condenser 6 and the antenna V may be employed. In Figs. 3- and 4 an autotransformer, and in Fi 5 a transformer having two separated win ings,

- are shown by way of example.

It will be apparent from the foregoing, that my invention includes the use of a vibratory electromotive force with either of the two types of continuously-oscillating circuits above referred to.

I claim:

1. In an electromagnetic wave radiating age across the gap will rise abruptly to its maximum before the condenser begins to discharge thercacross,

2. In an electromagnetic wave'radiating system, a circuit including in series an inductance, a condenser and two separated arc-electrodes, an antenna associated with said circuit and a generator of vibratory electromotire force, operatively connected with said are electrodes, and so arranged that the variation of current amplitude with time is practically zero throughout the greater portion of the continuance of a half-cycle.

In an electromagnetic wave radiating system, a circuit including in series an inductance, a condenser and two separated arc=electr nles, an antenna associated with said circuit, a source of vibratory electromotive force and connections having large impedance between said source of electromotive force and said arc-electrodes, the separation of said arc-electrodes being such that the voltage across the gap will rise abruptly to its maximum before the condenser begins to discharge thereacross, at each half cycle of operation.

t. A circuit including in. series an inductance, a condenser and two separated arc-electrodes, in combination with a generator of vibratory electrornotive force operof vibratory electromotive force, whereof the variation of amplitude with time is practically zero throughout the greater portion of the continuance of a half cycle, operatively connected with said arc-electrodes.

(3. A circuit including in series an inductance, a condenser and two separated arcelect-rodes in combination with a source of vibratory elcctromotive force and connections having large impedance between said source of electromotive force and said arcelectrodes, the separation of said arc-electrodes being so related to the amplitude of .said electromotive force as to cause an electrical are to be developed therebetween.

In testimony whereof,

THOMAS I. GALLAGHER, GEO. K. Woomvonrn.

I have hereunto- 

